Hey cosmin242,
Thanks for using Apple Support Communities! I understand you aren't getting the Alarms on your Apple Watch as expected. I definitely depend on my Alarms to be reliable, and want to make sure you're able to the same.
To start, if you haven't already done so, I recommend restarting both your iPhone and your Apple Watch. You can find the steps for restarting in the links below.
Restart your iPhone
How to restart your Apple Watch
You may also want to consider checking for available software updates for both your Apple Watch and iPhone. You can see how to update your device using the resources below.
Update your iPhone, iPad, or iPod touch
Update your Apple Watch
If this behavior continues, would you mind answer the questions below? This will give us a bit more information on the behavior and help get you pointed toward a resolution .
Do alarms that you set on the Apple Watch work as expected? You can see how to set alarms with your watch here: Add an alarm on Apple Watch
Does the alarm go off on your iPhone without issue, and just not on the Apple Watch?
Is this every alarm, or only some?
Thanks again, and have a great day!